Modified urea-formaldehyde resin

ABSTRACT

A resinous product comprising a curable urea-formaldehyde resin modified by a nitroalkanol and having particular utility for treating textiles and non-woven cellulose products to provide permanent press and wrinkle-resistant characteristics.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of Applicants' copendingapplication Ser. No. 25,502 filed Mar. 30, 1979 now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to urea-formaldehyde resins. In a particularaspect this invention relates to modified urea-formaldehyde resinshaving particular utility for treating textiles and non-woven celluloseproducts.

The importance of dimensional stability, such as wrinkle resistance anddurable press properties in textile fabrics and non-woven celluloseproducts are well established and are of great importance and economicvalue to the textile industry. The majority of textile articles, bothwearing apparel and household articles, available in the market-placeexhibit these properties to some beneficial degree. Although manysynthetic fibers inherently possess resiliency and wrinkle resistance,fabrics containing cellulose fibers must be chemically treated toacquire these important properties needed for the modern textile market.

In addition to wrinkle resistance and permanent press properties, it ishighly desirable that non-woven cellulosic products display good wetstrength characteristics. Yet most paper goods are especially deficientin wet strength unless they are treated.

The principal chemical treatments which produce wrinkle resistance anddurable press properties in cellulose containing textiles and non-wovenproducts are those in which the cellulose molecules are crosslinked,generally by reaction of a di- or polyfunctional agent with thecellulose. Many of the agents employed by the textile processingindustry to produce durable press properties in cellulosic fabrics areN-methylol adducts. To enhance the reactions between the cellulose andthese adducts many compounds or catalysts may be employed.

At present, urea-formaldehyde resins modified with glyoxal are used inlarge volume. However, glyoxal is a high-cost raw material and it wouldbe advantageous to employ a more economical modified urea-formaldehyderesin.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a modifiedurea-formaldehyde resin.

It is another object of this invention to provide modifiedurea-formaldehyde having particular utility for treating textiles andnon-woven cellulose products.

Other objects of this invention will be apparent to those skilled in theart from the description herein.

It is the discovery of this invention to provide a resinous productcomprising a curable urea-formaldehyde resin modified with from 0.25 to3.0 moles per mole of urea of a nitroalkane or of a nitroalkanol, saidnitroalkanol being represented by the formula ##STR1## where R ishydrogen, methyl, ethyl or hydroxymethyl.

In place of the nitroalkanol, there can be substituted a nitroalkane of1-3 carbon atoms in an amount equimolar to the amount of nitroalkanolemployed. Furthermore, a mixture in any proportion of nitroalkane andnitroalkanol of the above formula can be employed.

DETAILED DISCUSSION

The resinous product of this invention is a curable urea-formaldehyderesin modified by reaction with a nitroalkanol or with a nitroalkane ormixture thereof. The term "curable" is intended to mean that the resinis incompletely polymerized and is capable of further reaction withcrosslinking agents and the like.

Generally, but not necessarily, the modified resin is prepared byreacting the urea and formaldehyde in a mole ratio of about 1 to 1-5respectively at a neutral to alkaline pH, i.e. at a pH of from about 7to 11. Then the nitroalkanol is added and the reaction is continueduntil a solution clear at room temperature is obtained. The pH is thenadjusted to neutral or slightly acidic, e.g. 5-7 and heating iscontinued to finish the reaction.

In another embodiment of the invention, the formaldehyde and urea arereacted as above and a nitroalkane of 1 to 3 carbons atoms, or a mixtureof nitroalkane and nitroalkanol, is added. The remainder of the reactionis carried out as described.

In a third embodiment of the invention, the nitroalkanol is firstreacted with the urea at neutral to alkaline pH and then theformaldehyde is added and the reaction is carried to completion asdescribed above.

In a fourth embodiment of the invention, the formaldehyde andnitroalkane are reacted at alkaline pH, then urea is added and thereaction is continued to completion.

In still another embodiment, it is contemplated that alkylolated ureasare used in place of urea on an equimolar basis. These alkylolated ureasare known in the art and can be the mono- or dialkylolated compounds.The alkylol chain length can be of from 1 to 5 carbon atoms. Such ureasyield resins especially useful as adhesives.

It is also contemplated that, rather than prepare the urea-formaldehydeportion of the resin, a commercially-available, curable resin can beemployed in the reaction.

It is still yet another embodiment of this resin to react theurea-formaldehyde resin with up to 1.5 moles of glyoxal per mole of ureabefore reacting with the nitroalkanol or nitroalkane or mixture thereof.It is also contemplated that melamine can be employed as a cross-linkingagent.

The formaldehyde used in the practice of this invention is preferablythe 37% commercial grade. However, other formaldehyde sources such assolutions of formaldehyde in lower aliphatic alcohols andparaformaldehyde can also be used.

The nitroalkanols useful in the practice are commercially available andinclude, but are not limited to, tris(hydroxymethyl)nitromethane;2-nitro-2-methyl-1,3-propanediol; 2-nitro-2-ethyl-1,3-propanediol;2-nitro-1-butanol and, preferably, 2-nitro-2-methyl-1-propanol. Mixturesof these nitroalkanols can also be used. It is understood that theinvention is not limited to these nitroalkanols. Other nitroalkanols areknown in the art and regarded as being the obvious equivalents of theforegoing.

The nitroalkanes useful in the practice of this invention arecommercially available and include nitromethane, nitroethane,1-nitropropane, 2-nitropropane and mixtures thereof. The totalnitroalkane is used in a proportion of about 0.5-1.0 mole, preferably0.75 mole, per mole of urea. It is understood that the invention is notlimited to these nitroalkanes. Others are known in the art and areregarded as being the obvious equivalents of the foregoing.

The resins of this invention are prepared by the preferred process ofreacting the formaldehyde and urea at a pH of about 7-11, preferably8.0-10.5 and particularly at about 10.0-10.5. The pH can be provided byany alkaline reagent many of which are known, viz. inorganic carbonates,bicarbonates, oxides or hydroxides, including those of ammonia, sodium,potassium and lithium. Sodium hydroxide is preferred.

The reaction of formaldehyde and urea is preferably, but notnecessarily, carried out under alkaline conditions at elevatedtemperatures of from about 40° C. to reflux temperature at ambientpressure, preferably at reflux temperature. When the reaction iscomplete, the temperature, if at reflux, is preferably lowered somewhat,e.g. to about 75°-80° and then the nitroalkane, or mixture thereof, isadded, preferably slowly. After the addition is finished, the reactionis continued at about 75°-80° C. until a solution clear at roomtemperature is obtained. The reaction mixture is further cooled to about55°-65° C. and the pH is adjusted to about 5.0-7.0. The pH adjustmentcan be effected with any watersoluble mineral or organic acid. Generallya dilute acid such as dilute hydrochloric, phosphoric, sulfuric,p-toluene sulfonic, etc. will be used. The heating period is thencontinued at 55°-60° C. about one more hour to ensure complete reaction.The reaction product is then allowed to cool and if desired can bediluted to about 25-45% solids, which hastens the cooling process.

A 25% solution of the resin is preferred for treating the textile orother non-woven, cellulosic object. Preferably it is used with acatalyst, e.g. magnesium or zinc chloride. It is convenient to preparethe catalyst as a 25% aqueous solution and mix one part of the catalystsolution with four parts of the 25% resin solution. The textile or othernon-woven, cellulosic object is then saturated with the mixture, pressedto about a 60% wet pickup, then heated at, e.g., about 350° F. to curethe resin.

It is contemplated that the products and objects which will benefit fromthe wrinkle resistance conferred by the resin of the present inventionwill include but will not be limited to those made from natural fibers,principally wool and cellulose, both woven and non-woven. Of the wovenfibers, cotton fabrics are the ones which are expected to receive themost benefit. Non-woven fabrics are usually made from cellulose fibers,e.g. wood fibers, and are used extensively. While much of it goes todisposable items where wrinkle resistance may not be of greatimportance, still the market for durables is increasing especially inclothing interliners, bedding, carpets, draperies, etc., where wrinkleresistance is important. Actually, it is contemplated that any cellulosecontaining product, such as paper goods will benefit from treatment withthe resin, and the term fabric as used herein is intended to encompasssuch cellulose-containing product.

The invention will be better understood with reference to the followingexamples. It is understood that the examples are intended forillustration only and it is not intended that the invention be limitedthereby.

EXAMPLE 1

Into a reaction vessel fitted with a stirring means and a heat sourcethere was delivered 534 g of 37% formaldehyde (6 moles) and 180 g ofurea (3 moles). The mixture was stirred until homogeneous, then the pHwas adjusted to 8.0 with dimethylaminomethylpropanol. The mixture washeated to 45° C. for 70 minutes, then to 60° C. at which time the pH wasadjusted to 8.5-9.0 and a mixture containing 100.1 g of 2-nitropropaneand 33.39 g of 1-nitropropane (total of 1.5 moles) was added dropwise.The reaction was continued at 60° C. for 30 minutes after which theproduct was cooled and diluted to 25% solids. The pH was adjusted to 7.0using acetic acid. There was then added 25% of magnesium chloridecatalyst based on the solids content.

The wrinkle recovery was determined by Test Method 66-1968 of theAmerican Association of Textile Colorists and Chemists. A piece ofcotton cloth, unsized, was dipped into the resin solution, patted dryand stretched, then placed in an oven at 355° F. for ninety seconds. Tenspecimens, 40 mm long and 15 mm wide, were cut from the cloth, five withtheir long dimension parallel to the warp and five with their longdimension parallel to the filling. The recovery angle was thendetermined as set forth in the test method on test specimens. The valueswere averaged and expressed as total recovery angle. Similar specimenswere treated with a commercial product, "Permafresh LP", marketed by SunChemical Product for use as control. The results obtained are given inTable 1.

A sample of non-woven cellulosic material is treated with this resin. Ithas a high wet strength and good dimensional stability.

EXAMPLE 2

The experiment of Example 1 was repeated in all essential details exceptthat after addition of the nitroalkanes, the mixture was heated for onehour instead of 30 minutes. The results are given in Table 1.

EXAMPLE 3

Into a reaction vessel fitted with a stirring means and a heat source,there was delivered 178 g of 37% formaldehyde (2 moles) and 60 g of urea(1 mole). The ingredients were thoroughly mixed and the pH was adjustedto 8.0-8.2 using dimethylaminomethylpropanol. The temperature was raisedto 45° C. for 70 minutes and the pH was readjusted to 8.5-9.0. A mixturecontaining 11.3 g of 1-nitropropane and 33.37 g of 2-nitropropane (atotal of 0.5 moles of nitroalkane) was added dropwise over a 45 minuteperiod. The pH was then adjusted to 7.0 and was then diluted to 25%solids.

Cotton cloth was treated as described in Example 1 and the recoveryangle was determined. The result is given in Table 1.

A sample of non-woven cellulosic material is treated with this resin. Ithas a high wet strength and good dimensional stability.

EXAMPLE 4

The experiment of Example 3 was repeated in all essential details except44.5 g of the nitropropanes were employed in a 1:1 ratio. The resultsare given in Table 1.

EXAMPLE 5

The experiment of Example 3 was repeated in all essential details exceptthat after the nitroalkanes were added, the heating period was continuedfor 30 minutes. The results obtained are given in Table 1.

                  Table 1                                                         ______________________________________                                        Example  Color       Recovery    Tensile                                      Number   Gardner     Angle, °                                                                           Strength                                     ______________________________________                                        1        --          258         31                                           2        --          266         32                                           3        1           243         20                                           4        1           225         22.5                                         5        1           265         35                                           Control  1           231         14.5                                         ______________________________________                                    

EXAMPLE 6

Aqueous 37% formaldehyde 324.3 g (4 moles of formaldehyde) was deliveredto a 3-necked round bottom flask equipped with a stirrer, a thermometer,condenser and heat source. The pH was adjusted to 10.5 with 10% sodiumhydroxide solution and then heated to reflux. Urea 60 g (1 mole) wasadded and heating at reflux was continued for 15 minutes. The mixturewas cooled to about 78° C. and 2-nitropropane 67.5 g (0.75 mole) wasadded. The temperature was held constant until the mixture becamehomogeneous (about 15-20 minutes). The mixture was then cooled to about60° C. and the pH was adjusted to 5.0 with phosphoric acid and heatingat 60° C. was continued for an hour. Deionized water was added in aquantity sufficient to produce a 25% total solids content.

A 25% solution of catalyst was prepared by dissolving 100 g of MgCl₂.6H₂O in 87.4 g of water. Four parts of the resin solution was mixed withone part of catalyst and cloth samples, as described in Example 1, weretreated with the resulting solution, then pressed to a 60% wet pickup.On drying this procedure gave 9-12% of resin, dry weight, on the cloth.The cloth samples were then stretched taut and were baked at 225° F. fortwo minutes and at 325° F. for three minutes. The recovery angle wasthen determined. Similarly, cloth samples were treated with acommercially available product (Permafresh LF) as a control. The resultsobtained are given in Table 2.

A sample of non-woven cellulosic material is treated with this resin. Ithas a high wet strength and good dimensional stability.

EXAMPLES 7-9

The experiment of Example 6 was repeated in all essential details exceptthat in place of 4 moles of formaldehyde, there was substituted 3.9, 3.8and 3.7 moles respectively. The results are given in Table 2.

                  Table 2                                                         ______________________________________                                        Example  Formaldehyde Recovery    Tensile                                     Number   moles        Angle, °                                                                           Strength                                    ______________________________________                                        6        4            306         23.5                                        7        3.9          297         26.0                                        8        3.8          295         23.5                                        9        3.7          320         20.5                                        Control               277         15.0                                        ______________________________________                                    

EXAMPLES 10-15

The experiment of Example 6 was repeated in all essential details exceptthat the 2-nitropropane content was varied from 1 mole (90 g) to 0.95,0.90, 0.85, 0.80 and 0.75 for Examples 10-15 respectively. The resultsare given in Table 3.

                  Table 3                                                         ______________________________________                                        Example   2-NP       Recovery    Tensile                                      Number    moles      Angle, °                                                                           Strength                                     ______________________________________                                        10        1.00       296         17.8                                         11        .95        274         17.4                                         12        .90        299         18.3                                         13        .85        288         21.4                                         14        .80        286         22.7                                         15        .75        306         23.4                                         ______________________________________                                    

EXAMPLE 16

Formaldehyde, 37% aqueous solution, 810 g (10 moles) was delivered to around bottom flask and urea 120 g (2 moles) was added. A stirrer,condenser and thermometer were attached and the pH was adjusted to 10.52using 50% aqueous sodium hydroxide. The flask and contents were heatedto 60° C. while stirring and were maintained at that temperature for 4hours (only 2 hours was intended). The pH was then adjusted to 9.6 using20% hydrochloric acid solution and 2-nitro-2-methyl-1-propanol, 203.4 gof a 64.4% aqueous solution (110 moles), was added. After 15 minutes, asample cooled to room temperature was clear. Additional hydrochloricacid to adjust the pH to 6.0 was added and the temperature wasmaintained at 60° C. for one hour longer. It was then diluted with 75.5ml of water.

A sample of the foregoing solution was treated with magnesium chloridecatalyst and the resulting solution was used to treat a standard textilesample. The recovery angle was 296°. Similarly, a textile sample treatedwith a zinc nitrate-catalyzed resin had a recovery angle of 300°.

A sample of non-woven cellulosic material is treated with this resin. Ithas a high wet strength and good dimensional stability.

EXAMPLE 17

The experiment of Example 16 was repeated in all essential detailsexcept that the weight of formaldehyde was reduced to 648 g (8 moles),the nitromethylpropanol was increased 277 g (1.5 moles) and the heatingperiod at pH 10.5 was 2 hours. The recovery angle of the magnesiumchloride catalyzed resin-treated fabric was 289° and that of the zincnitrate catalyzed was 304°.

EXAMPLE 18

The experiment of Example 17 was repeated in all essential detailsexcept that the amount of 2-nitro-2-methyl-1-propanol was increased to375 g (1 mole). When magnesium chloride catalyst was used, a recoveryangle of 299° was obtained and when zinc nitrate was used, the recoveryangle was 294°.

EXAMPLE 19

The experiment of Example 18 was repeated in all essential detailsexcept that the amount of NMP was reduced to 203 g (1 mole). Whenmagnesium chloride was used as the catalyst, the recovery angle was295°. When zinc nitrate was used as the catalyst, the recovery angle was299°.

EXAMPLE 20

The experiment of Example 17 was repeated in all essential detailsexcept that the amounts of urea and formaldehyde were reduced to 60 g (1mole) and 325 g (4 moles) respectively and after they had been heatedfor 2 hours, 72 g of a 40% solution of glyoxal (0.5 mole) was added andthe heating was continued an additional hour at 50° C. The pH wasreduced to 9.0 and heating was continued for another hour. The pH haddropped to 8.35 so it was increased to 9.2 and 2-nitropropane 66.7 g(0.75 mole) was added. After 15 minutes, the pH was reduced to 6.03 andafter another hour of heating, the reaction was terminated. Whenmagnesium chloride was used as the catalyst, the recovery angle was 278°and when zinc nitrate was used, the recovery angle was 287°.

A sample of non-woven cellulosic material is treated with this resin. Ithas a high wet strength and good dimensional stability.

EXAMPLE 21

The experiment of Example 16 is repeated in all essential details exceptthat the amount of 2-nitro-2-methyl-1-propanol was reduced to 55 molesand 2-nitropropane, 55 moles, is added. A textile sample is treated withthis resin. It has a high recovery angle when tested for wrinkleresistance. A sample of paper product is treated with this resin. It hashigh wet strength and good dimensional stability.

We claim:
 1. A resinous product comprising a curable ureaformaldehyderesin modified with from 0.25 to 3.0 moles of a nitroalkanol per mole ofurea, said nitroalkanol being represented by the formula ##STR2## whereR is hydrogen, methyl, ethyl or hydroxymethyl.
 2. The resinous productof claim 1 wherein the urea is provided by the methyl, ethyl, propyl orbutyl ether of urea.
 3. The resinous product of claim 1 wherein theurea-formaldehyde resin is modified with up to 1.5 mole of glyoxal permole of urea prior to reaction with the nitroalkanol.
 4. The product ofclaim 1 wherein the nitroalkanol is tris(hydroxymethyl)nitromethane. 5.The product of claim 1 wherein the nitroalkanol is2-nitro-2-methyl-1,3-propanediol.
 6. The product of claim 1 wherein thenitroalkanol is 2-nitro-2-ethyl-1,3-propanediol.
 7. The product of claim1 wherein the nitroalkanol is 2-nitro-2-methyl-1-propanol.
 8. Theproduct of claim 1 wherein the nitroalkanol is 2-nitro-1-butanol.
 9. Aresinous product comprising a curable ureaformaldehyde resin modifiedwith a nitroalkane of 1 to 3 carbon atoms or mixture thereof in a moleratio of from 0.25 to 3.0 per mole of urea.
 10. The product of claim 9wherein the nitroalkane is nitromethane.
 11. The product of claim 9wherein the nitroalkane is nitroethane.
 12. The product of claim 9wherein the nitroalkane is nitropropane.
 13. A method for thepreparation of the resinous product of claim 1 comprising the steps of(a) reacting urea and formaldehyde in a mole ratio of about 1:1-5respectively at neutral or alkaline pH; (b) reacting the product of step(a) with from 0.25 to 3 moles per mole of urea of a nitroalkanolrepresented by the formula ##STR3## where R is hydrogen, methyl, ethylor hydroxymethyl; (c) adjusting the pH to about 5 to 7, and (d)completing the reaction.
 14. A method for the preparation of the curableresinous product of claim 9 comprising the steps of (a) reactingformaldehyde and urea in a mole ratio of about 1-5:1 respectively at aneutral or alkaline pH; (b) reacting the product of step (a) with0.25-3.0 moles of a nitroalkane of 1 to 3 carbon atoms or mixturethereof until a solution clear at room temperature is obtained; (c)adjusting the pH to about 5 to 7, and (d) completing the reaction.
 15. Amethod for the preparation of the resinous product of claim 1 comprisingthe steps of (a) reacting urea with from about 0.25 to 3 moles of anitroalkanol represented by the formula ##STR4## wherein R is hydrogen,methyl, ethyl or hydroxymethyl; (b) reacting the product of step (a)with from about 1 to 5 moles of formaldehyde at a pH of from 7 to about11; (c) adjusting pH to about 5 and (d) completing the reaction.
 16. Amethod for the preparation of the resinous product of claim 9 comprisingthe steps of (a) reacting formaldehyde with a nitroalkane of from 1 to 3carbon atoms in a mole ratio of from 1 to 5 moles of formaldehyde permole of the urea of step (b) and from 0.25 to 3.0 moles nitroalkane permole of urea at a pH of about 7 to 11; (b) reacting the product of step(a) with about 1 mole urea; (c) adjusting the pH to about 5 to 7 and (d)completing the reaction.
 17. The method of any of claims 13, 14, 15 or16 wherein the alkaline pH is 10.0 to 10.5.
 18. The method of claim 14or claim 16 wherein the nitroalkane is added in a mole ratio of about0.75 to 1.0 to one of urea.
 19. The method of claim 14 or claim 16wherein the reaction with the nitroalkane is carried out at about75°-80° until a solution clear at room temperature is obtained.
 20. Themethod of claim 14 wherein the pH is adjusted to about 5 when the clearsolution is obtained.
 21. The method of either claim 14 or 16 whereinthe nitroalkane is nitromethane.
 22. The method of either claim 14 or 16wherein the nitroalkane is nitroethane.
 23. The method of either claim14 or 16 wherein the nitroalkane is 1-nitropropane.
 24. The method ofeither claim 14 or 16 wherein the nitroalkane is 2-nitropropane.
 25. Themethod of claim 14 or claim 16 wherein glyoxal is reacted with theproduct of step (a) in an amount of up to 1.5 moles per mole of urea.26. The resinous product of claim 9 wherein the urea-formaldehyde resinis modified with up to 1.5 moles of glyoxal per mole of urea prior toreaction with the nitroalkane.
 27. The resinous product of either ofclaims 1 or 9 wherein the urea-formaldehyde resin is modified with amixture of nitroalkane and nitroalkanol in any proportion.